BUILDING A WORLD OF DIFFERENCE. Briefing for Resident Engineers

Transcription

1 Introduction to Safe Working in Excavations Briefing for Resident Engineers

2 Planning excavations - considerations Stability of excavations ground conditions People, material and vehicles falling into excavations Undermining nearby structures Existing services Confined space Other considerations Page - 2

3 Excavations Not B&V site Page - 3

4 Stability of excavations ground conditions Nature of the ground and any ground water conditions Type of soil, contamination Groundwater level and soil permeability Depth of excavation Location of the work Proximity of roads Existing structures and services Working space Effect of atmospheric pressure Page - 4

5 Prevent collapse Battering back to a safe angle Shoring with drag box, sheet piles or timber etc Page - 5

6 Prevent collapse This excavation is supported by timber and props. The boards extend above the edge of the excavation to act as toe boards and guard rails are provided to prevent falls into the excavation. Safe access is provided by a tied ladder, exposed services are supported Page - 6

7 Not B&V site Page - 7

8 People, material and vehicles falling into excavations Place barriers around the excavations to prevent people falling In public areas excavations shall be protected at all times Keep vehicles away from the edges of the excavations Page - 8 Place barriers or baulks etc Ensure there is suitable signing and lighting in roadways

9 People, material and vehicles falling into excavations Do not place spoil close to the sides of excavations Do not store materials close to the sides of excavations Place stop logs to prevent vehicles or plant overturning into the excavation Page - 9

10 Undermining nearby structures Check for nearby structures Survey foundations Shallow foundations Page - 10

11 Existing services Check plans (buried and overhead services) Cable and service locators Safe digging practices Protection and support of services Emergency arrangements Old backfilled trenches possible loose material Page - 11

12 Confined Space (refer to previous session) Do not use petrol or diesel engines within or adjacent to an excavation without considering the need for ventilation soils derived from chalk or limestone which are in contact with acidic groundwater can give off carbon dioxide gases such as methane or hydrogen sulphide can seep into pits from contaminated ground or damaged services Page - 12

13 Confined spaces methane from geological sources can migrate into excavations (especially in deep shafts and tunnels) activities within the excavation can give off toxic fumes poor ventilation of the excavation can result in pockets of toxic gases or oxygen-deficient air Page - 13

14 Other considerations Chemicals used as part of a work process Safe access and egress for workers Adequate lighting for workers Page - 14

15 Procedures & Guidance P916; Guidance: Earthworks G916A, Minimising Risks G916B, Avoid Buried Services G916C Permit to dig F912/5 Inspections F916/3 Page - 15

16 Plan the work Assess the risks and prepare the method statement Ensure all necessary plant and equipment is in place and is suitable Check existing services hand dig in vicinity Implement permit to dig Ensure people fully understand the work to be done and the limits of the work Ensure safe access and egress Ensure emergency arrangements understood Page - 16

17 Things to check when work is in progress Check assessment, method statement and permit are in place Ensure any temporary works are installed correctly, eg props and wedges are tight Check for signs of damage or overstress in support structures Check for water or soil seeping into the excavation Check for signs of earth peeling or cracking Page - 17

18 Things to check when work is in progress Ensure existing services are located, marked and supported as necessary Check that there is adequate ladders and that they are in good condition, secured and used correctly Ensure the spoil heaps are kept back Ensure that there are adequate barriers, notices and lighting Ensure traffic is kept well back from edge of the excavation and there are stops for tipping plant Page - 18

19 Things to check when work is in progress Gas monitoring in place People are wearing the correct PPE People are not working too close to machines Excavations covered or backfilled at the end of the shift Ensure the removal of temp supports is done safely Emergency arrangements in place Daily inspections being carried out Page - 19